Graphical grief

From
Francis Massen

Your diagram comparing natural solar radiation with man-made effects is misleading and could be seen as dishonest (10 February, p 9). It shows two discs to compare these effects, the larger one having about 13 times the diameter of the smaller one. As you write, the increase in solar radiative forcing is 0.12 watts per square metre, compared to man-made effects accounting for 1.6 W/m2, according to the Intergovernmental Panel on Climate Change&colon; that is, about 13 times as much. But discs are seen as surfaces, not as diameters, in a comparison&colon; thus the graphic suggests that …